1. Field of the Invention
The invention pertains to a method and apparatus for honing the pad engaging surfaces for vehicle brake rotors wherein superior finish characteristics are attained and wherein a wear resistant surface is produced.
2. Description of the Related Art
Vehicle brake rotors or drums basically consist of a hub attached to the vehicle wheel rotatable about the wheel axis of rotation. A radially extending flange depending from the hub periphery includes opposed finished surfaces engageable by the brake pads mounted in a caliper extending over the flange. The brake pads are hydraulically operated to selectively engage the rotor surfaces in a frictional manner to brake the vehicle wheels.
To prevent excessive pad wear, the rotor pad engaging surfaces must be relatively smooth, and are ground, turned or otherwise machined. As vehicle brake rotors are usually formed of a high strength aluminum alloy, it is important that the finishing operation produce the desired smoothness without galling, and difficulty has been encountered in achieving the desired brake rotor pad engaging finish.
High strength aluminum alloy brake rotor surfaces will, during the normal course of wear and engagement by the brake pad, usually form a thin oxidized surface layer resistant to wear. This oxidized layer directly engages the pads, and results from the high temperatures resulting from the frictional engagement of the brake rotor surface and brake pad. In current practice, the brake rotor is not initially provided with this wear resistant oxidized layer, and its existence is haphazardly achieved by the heat generated during braking. In some instances, rather than an oxidized wear resistant layer being formed upon the rotor braking surface, a galling occurs between the surface and the brake pad which prevents the formation of the oxidized layer, and produces a roughness which accelerates the brake pad wear requiring premature pad replacement.